Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$92.30	12.703%	$104.0249	$104.02	$104.00	$104.00
Purchase #2	$239.34	4.616%	$250.3879	$250.39	$250.40	$250.40
Purchase #3	$249.54	13.388%	$282.9484	$282.95	$282.95	$282.90
Purchase #4	$93.31	11.122%	$103.6879	$103.69	$103.70	$103.70
Purchase #5	$89.43	3.381%	$92.4536	$92.45	$92.45	$92.50
Purchase #6	$18.98	13.459%	$21.5345	$21.53	$21.55	$21.50
Purchase #7	$143.26	12.484%	$161.1446	$161.14	$161.15	$161.10
7 purchase totals =	$926.16		$1,016.1818	$1,016.17	$1,016.20	$1,016.10